There are several known types of surgical staplers in which the stapling function takes place at a location which is relatively remote from the location at which the stapler is held and actuated by the operator. Examples of such staplers are the circular anastomosis surgical staplers shown illustratively in Akhalaya et al, U.S. Pat. No. 3,193,165 and Noiles U.S. Pat. No. 4,351,466. Typically, instruments of the types exemplified by these references, include a main body which is provided with a staple-holding assembly at its distal end and a longitudinal connecting shaft which is axially movable within the body and extends outwardly from the distal end of the body. The anvil assembly is fixed or threaded onto the free end of the shaft so that, when the shaft is caused to reciprocate with respect to the body, the anvil assembly can be caused to move toward and away from the staple-holding assembly. When such an instrument is used, tissue to be stapled is fastened about the staple-holding assembly and about the anvil assembly and clamped between them. The clamped tissue is then stapled by driving a plurality of staples from the staple-holding assembly so that the ends of the staples pass through the tissue and are clinched by contact with the anvil assembly. The forces required to operate the instrument to eject the staples are applied by the operator of the instrument to one or more actuator elements located at or near the proximal end of the body of the instrument. Means are also provided for causing the shaft to advance and retract. These means are generally at the proximal end of the body of the instrument. Thus, the distal and proximal portions of the instrument are joined by the longitudinal connecting shaft structure along which the actuating forces and motions are transmitted to the distal operating elements. This type of construction, including relatively widely-spaced distal and proximal portions, is conventionally used.
In a typical procedure, e.g. in colon surgery, the sections of the colon to be joined are, respectively, secured manually about the staple-holding assembly and the adjacent shaft portion and about the anvil of the instrument and the adjacent shaft portion. The head and anvil are then drawn together by causing the longitudinal connecting shaft to the end of which the anvil assembly is rigidly mounted to retract in the instrument body, so that the anvil assembly approaches the staple-holding assembly carried by the instrument body, and thereupon the stapling operation ensues.
A serious problem with the procedure just described is that, when using surgical stapling devices of the prior art, the surgeon must work "blind" to some extent since the staple-holding assembly and the anvil assembly are each rigidly connected to the instrument at a limited distance from each other and he must apply the tissue in a limited space and, at times, he cannot fully view all parts of the tissue to be stapled. Vision is limited by the rigid relationship between the staple-carrying assembly and the anvil assembly so that the gap or distance between the two is often unduly confining. In addition, because the anvil blocks the surgeon's view, as frequently happens, if the purse-string sutures fixing the bowel around the instrument are loose or incomplete, after the instrument is fired and withdrawn, the anastomosis has to be redone. Even worse, occasionally, this is not recognized and a leak can occur, resulting in pelvic infection or worse.
Currently, surgical stapling instruments are constructed so that they can be economically discarded after use in a single surgical procedure, i.e., so-called disposable instruments. Typically, a disposable instrument is sold in sterile condition in packaging designed to keep the instrument sterile until used. After the instrument has been used in a surgical procedure, it is discarded. In this way, all difficulty and expense associated with cleaning, sterilizing, and reloading the instrument are entirely avoided.
For an instrument to be economically disposable after use in only one surgical procedure, however, the cost of the instrument must be relatively low. This generally dictates that as much as possible of the instrument be made of inexpensive materials such as plastics, and that the instrument have the simplest and lightest possible construction. These criteria for an economically disposable instrument require a non-complicated construction for the instrument.